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WO1992019855A1 - Systeme stirling a pistons libres et a detente de gaz comprime relative - Google Patents

Systeme stirling a pistons libres et a detente de gaz comprime relative Download PDF

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Publication number
WO1992019855A1
WO1992019855A1 PCT/US1992/002305 US9202305W WO9219855A1 WO 1992019855 A1 WO1992019855 A1 WO 1992019855A1 US 9202305 W US9202305 W US 9202305W WO 9219855 A1 WO9219855 A1 WO 9219855A1
Authority
WO
WIPO (PCT)
Prior art keywords
gas spring
piston
displacer
diameter
free
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1992/002305
Other languages
English (en)
Inventor
Nicholas Gerald Vitale
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Soluna Holdings Inc
Original Assignee
Mechanical Technology Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mechanical Technology Inc filed Critical Mechanical Technology Inc
Publication of WO1992019855A1 publication Critical patent/WO1992019855A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B11/00—Reciprocating-piston machines or engines without rotary main shaft, e.g. of free-piston type
    • F01B11/02—Equalising or cushioning devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G1/00—Hot gas positive-displacement engine plants
    • F02G1/04—Hot gas positive-displacement engine plants of closed-cycle type
    • F02G1/043—Hot gas positive-displacement engine plants of closed-cycle type the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines
    • F02G1/0435—Hot gas positive-displacement engine plants of closed-cycle type the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines the engine being of the free piston type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
    • F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
    • F16F15/023—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using fluid means
    • F16F15/0232—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using fluid means with at least one gas spring

Definitions

  • the present invention relates to Stirling cycle systems, and more particularly to a new and improved Free-Piston Stirling cycle system (such as a Stirling cycle engine) of the relative gas spring type especially adapted for operation at frequencies of 50 Hz. and above.
  • Free-Piston Stirling systems of which I am aware that is, systems wherein the force required to impart motion to the displacer is generated by the relative motion between the displacer and the power piston
  • the ration of the diameter of the gas spring piston to the diameter of the displacer is not more than about 0.30, and all such systems are limited to operation of no greater than 30 Hz. I have discovered that high frequency operation (50 Hz.
  • a Stirling cycle engine operates on the principal of heating and cooling a working fluid (gas) , with the expansion and compression of the gas utilized to perform useful work.
  • a working gas is shuttled between two stationary volume changers or spaces, an expansion space and a compression space. This shuttling is typically performed by a displacer.
  • the Free-Piston Stirling engine is desirable for a number of reasons, including that it is self-starting and can be pressurized and enclosed within a hermetically sealed housing where no external gas seal is required.
  • Free-Piston Stirling cycle systems offer advantages, especially for use as pumps, compressors, electrical power generators, cryocoolers, and the like.
  • the operation of a Free-Piston Stirling engine is described in the foregoing Walker text, and is now well known in the art.
  • One embodiment of a known prior art relative gas spring configuration Free- Piston Stirling engine system is shown and described in more detail in U.S. Patent No. RE. 30,176.
  • the simplest Free-Piston Stirling engine configuration is of the type wherein the force required to impart motion to the displacer is generated by the relative motion between the displacer and the power piston.
  • Such a Free-Piston Stirling system is referred to herein as being of the "relative gas spring configuration.”
  • the foregoing relative gas spring configuration Free-Piston Stirling system while providing a desirable, mechanically simple configuration is limited to low frequency operation, that is, to frequencies no greater than 30 Hz.
  • Free-Piston Stirling systems of an "absolute gas spring configuration” have been devised.
  • absolute gas spring configuration Free-Piston Stirling systems a stationary support is provided between the displacer and the power piston such that the spring force required to reciprocate the displacer is generated by the relative motion between the displacer and the stationary housing.
  • One embodiment of a prior art absolute gas spring configuration Free-Piston Stirling engine system is shown and described in detail in U.S. Patent No. 4,387,567, which is assigned to the same assignee as the present invention.
  • the ratio of the diameter of the gas spring piston to the diameter of the displacer is about 0.30. I have discovered, however, that reliable high frequency operation (that is, 50 Hz. and above) , can be achieved in a mechanically simple, relative gas spring configuration Free- Piston Stirlig system by making the ration of the diameter of the gas spring piston to the diameter of the displacer at least 0.50.
  • the new and improved relative gas spring configuration Free-Piston Stirling cycle system comprises a pressurized sealed housing and a cylinder of selected diameter, disposed within the housing.
  • a power piston is mounted for reciprocation within or about one region of the cylinder, and a displacer of selected diameter is mounted for reciprocation within or about another region of the cylinder.
  • the Free-Piston Stirling system further includes a relative gas sprig means arranged and constructed to generate a force by the relative motion between the displacer and the power piston to impart movement to the displacer.
  • the relative gas spring means comprises a gas spring space, and a rod coupling the displacer with the gas spring space and defining a gas spring piston which terminates at the gas spring space.
  • the relative gas spring means is arranged and constructed so that the ratio of the diameter of the gas spring piston to the diameter of the displacer is at least 0.50.
  • Figure 1 is a schematic illustration of a prior art relative gas spring configuration, Free- Piston Stirling engine system wherein the force required to reciprocate the displacer is generated by the relative motion between the displacer and the power piston;
  • Figure 2 is a schematic illustration of a prior art absolute gas spring configuration Free- Piston Stirling engine system wherein the force required to reciprocate the displacer is generated by the relative motion between the displacer and the stationary housing;
  • Figure 3 is a schematic illustration of a relative gas spring configuration, Free-Piston Stirling system in accordance with this present invention wherein the force required to reciprocate the displacer is generated by the relative motion between the displacer and the power piston, and wherein the ratio of the diameter of the gas spring piston to the diameter of the displacer is at least 0.50; and
  • Figure 4 is a more detailed schematic sectional view of a relative gas spring Free-Piston Stirling system, incorporating the present invention, wherein the system is arranged in an opposed configuration, and is of the "nested type design" such as shown and described in the foregoing referenced Patent Application S.N. 484,216.
  • one reciprocating member such as the displacer
  • another reciprocating member such as the power piston
  • the gas spring piston may be similarly nested. That is, a member may be mounted for reciprocation either within the cylinder, or around or about the cylinder.
  • FIG. 1 is a schematic illustration of a known type of relative gas spring configuration, Free-Piston Stirling system.
  • the system comprises a suitable sealed pressurized housing 10 and three components: a power piston 12, a light weight displacer 14, and a cylinder 16.
  • a gas spring piston rod 18 passes into power piston 12 and couples the displacer 14 with the space 20.
  • This space 20 is referred to as the "relative gas spring space”.
  • the working space is that part of the cylinder which is above the power piston, and is divided into the compression space 22, between the piston and the displacer, and the expansion space 24, above the displacer.
  • the system also includes a heater 26, a cooler 28, and a regenerator 30, arranged between the hot expansion space 24 and the cold compression space 22.
  • a heater 26 a cooler 28, and a regenerator 30, arranged between the hot expansion space 24 and the cold compression space 22.
  • the spring force required to reciprocate the displacer is generated by the relative motion between the displacer 14 and the power piston 12. While mechanically simple, such relative gas spring configuration Free-Piston Stirling systems have heretofore been limited to low frequency operation. That is, to operation not over 30 Hz.
  • FIG 2 there is schematically illustrated a known absolute gas spring configuration, Free- Piston Stirling system.
  • One arrangement of such an absolute gas spring configuration Free-piston Stirling system is shown and described in the foregoing referenced Patent No. 4,387,567.
  • the absolute gas spring configuration, Free-Piston Stirling system allows for operation at higher frequency than that of the relative gas spring configuration system illustrated in Figure 1.
  • the system illustrated in Figure 2 similarly comprises a sealed pressurized housing 10, a power piston 12, a light weight displacer 14, and a cylinder. 16.
  • a stationary support 32 is provided between the displacer 12 and the stationary housing.
  • a gas spring piston rod 18 couples the displacer 14 with the space 34, which space 34 is coupled to the stationary housing 10 by means of stationary support 32.
  • Stirling system therefore, the force required to reciprocate the displacer is generated by the relative motion between the displacer and the stationary housing. Higher frequency operation is achieved with such an arrangement but at the expense of increased mechanical complexity and cost.
  • Figure 3 schematically illustrates a relative gas spring configuration Free-Piston Stirling system in accordance with the present invention.
  • the new and improved system of the present invention is similar in general construction to that illustrated in Figure 1, in that there is no stationary support 32 between the displacer 12 and the stationary housing. Accordingly, the system shown in Figure 3 is a relative gas spring configuration Free-Piston Stirling system wherein the force required to reciprocate the displacer is generated by the relative motion between the displacer and the power piston.
  • the novel and important difference between the arrangement of the present invention and that of the arrangement shown in Figure 1 is that in the relative gas spring configuration Free - Piston Stirling system of this present invention the ratio of the diameter d of the gas spring piston 18 to the diameter D of the displacer 14 is made to be at least 0.50.
  • FIG. 4 there is shown a more detailed schematic sectional view of a relative gas spring Free-Piston Stirling system, incorporating the present invention wherein the system is arranged in an opposed configuration, and is of the "nested type design", such as shown and described, for example, in the foregoing referenced Patent Application Serial No. 484-216.
  • the opposed arrangement is desireable since it can achieve a better balance for the system, and the nested design provides for ease of manufacture and low cost.
  • a Free-Piston Stirling system 40 incorporating the present I invention includes a sealed pressurized housing 42 with a central axis C-C. In the arrangement shown all components are shown disposed symmetrically about the axis C-C. For the sake of simplicity, only one side of the system is described in detail.
  • a thermodynamic assembly including a centrally disposed annular heater section 44 with heat exchanging coils 44' which provide the heat required for the thermodynamic section and thus acts like as a heat sink for the external environment.
  • this annular heater section may be replaced by a centrally located cold head as illustrated in the referenced Patent Application S.N. 484,216.
  • the system also includes a cylinder means defined by two concentric radially spaced apart walls 52 and 54, a power piston 56, and a displacer 58.
  • the power piston 56 is slidably mounted on the outer piston cylinder wall 52 and is provided with a cap 60.
  • the cap 60, together with the two cylinder walls 52 and 54 and an end member 62 define the Stirling compression space 64.
  • Compression space 64 is connected to the regenerator 46 by axial passages 66.
  • Attached to cap 60 is the plunger 68 of a suitable electrodynamic motor 70 used to reciprocate the power piston 56.
  • Cap 60 also supports a hollow cylindrical gas spring rod constituting a gas spring piston 72 disposed for reciprocation with respect to a gas spring cylinder 74.
  • the displacer 58 includes a dome head 80 disposed in the common expansion space 50.
  • a tubular wall 82 extends rearwardly from the head 80 and is slidably disposed inside cylinder wall 54.
  • Suitable sealing and bearing means are provided between the walls 54 and 82 and also between wall 52 and power piston 56.
  • Suitable sealing is also provided between gas spring piston 72 and gas spring cylinder 74.
  • One end of gas spring cylinder 74 is connected to wall 82 by end member 62. The other end is terminated by a somewhat hemispherical cap 90.
  • gas spring piston 72, cap 60, gas spring cylinder 74, and cap 90 cooperate to define the space 92 forming a relative gas spring means, which is operative to generate the force required to impart motion to the displacer by the relative motion between the displacer and the power piston.
  • a plurality of conical heat shields 94 are disposed inside cap 90 to prevent radiative or convective heat exchange between the cap 90 and the rest of the Stirling system.
  • the ratio of the diameter d of the gas spring piston 72 to the diameter D of the displacer 58 is made to be at least 0.50.
  • the ratio of the diameter of the gas spring piston to the diameter of the displacer has always been less than 0.30. It has been discovered that because of this larger ratio of the diameter of the gas spring piston to the diameter of the displacer, a relative gas spring configuration Free-Piston Stirling can be reliably operated at much higher frequencies (50 Hz. and above) than was previously achievable with such a mechanically simple relative gas spring configuration.
  • a further advantage of the invention is that the displacement power input and relative gas spring are achieved in a relatively simple gas spring piston/cylinder arrangement and without the necessity for additional gas springs to achieve reliable operation at 50 Hz, and above.
  • Free-Piston Stirling systems constructed in accordance with this invention and employing only a single gas spring have been operated reliably at above 80 Hz.
  • the pressure difference across the gas spring piston/cylinder seal is made much lower than in previous configurations and, therefore, the clearance for such seal can be made larger without incurring excessive losses across the seal, which allows for lower manufacturing cost.
  • the present invention relates to new and improved Free-Piston Stirling heat systems, for such applications as compressors, pumps, electrical power generators, cryocoolers, and other like apparatus and systems having a wide range of applications, residential, commercial and industrial.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)

Abstract

Système Stirling à pistons libres comprenant un cylindre situé à l'intérieur d'un carter scellé et sous pression (10). Un piston de puissance (12) est conçu pour effectuer un déplacement alternatif à l'intérieur ou autour d'une autre zone du cylindre et définit avec ledit cylindre un espace de compression (22) et un espace de dilatation (24). Le piston de puissance (12) définit également un espace de détente de gaz comprimé (20) avec le cylindre. Un piston de détente de gaz comprimé (18) à diamètre présélectionné accouple le piston déplaceur (14) audit espace de détente de gaz comprimé (20), afin de créer une détente de gaz comprimé relative générant une force de déplacement alternatif du piston déplaceur par l'intermédiaire du déplacement relatif effectué entre le piston déplaceur et le piston de puissance. D'après l'invention, le rapport entre le diamètre du piston de détente de gaz comprimé (d) et le diamètre du piston déplaceur (D) est fixé à 0,50 au moins.
PCT/US1992/002305 1991-05-01 1992-03-23 Systeme stirling a pistons libres et a detente de gaz comprime relative Ceased WO1992019855A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US07/694,370 US5109673A (en) 1991-05-01 1991-05-01 Relative gas spring configuration free-piston stirling cycle system
US694,370 1991-05-01

Publications (1)

Publication Number Publication Date
WO1992019855A1 true WO1992019855A1 (fr) 1992-11-12

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Application Number Title Priority Date Filing Date
PCT/US1992/002305 Ceased WO1992019855A1 (fr) 1991-05-01 1992-03-23 Systeme stirling a pistons libres et a detente de gaz comprime relative

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WO (1) WO1992019855A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996006273A1 (fr) * 1994-08-20 1996-02-29 Karl Obermoser Moteur stirling a pistons synchrones

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4424319C1 (de) * 1994-07-09 1996-02-22 Harald Hofmann Heißgasmotor
US5904044A (en) * 1997-02-19 1999-05-18 White; William M. Fluid expander
US7171811B1 (en) * 2005-09-15 2007-02-06 Global Cooling Bv Multiple-cylinder, free-piston, alpha configured stirling engines and heat pumps with stepped pistons
US20070193266A1 (en) * 2006-02-17 2007-08-23 Stirling Cycles, Inc. Multi-cylinder free piston stirling engine
GB0803021D0 (en) * 2008-02-19 2008-03-26 Isis Innovation Linear multi-cylinder stirling cycle machine

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4802332A (en) * 1987-11-20 1989-02-07 Sunpower, Inc. Sliding surface lubrication particularly advantageous for a free piston stirling engine
US4945726A (en) * 1989-08-23 1990-08-07 Sunpower, Inc. Leaky gas spring valve for preventing piston overstroke in a free piston stirling engine

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4802332A (en) * 1987-11-20 1989-02-07 Sunpower, Inc. Sliding surface lubrication particularly advantageous for a free piston stirling engine
US4945726A (en) * 1989-08-23 1990-08-07 Sunpower, Inc. Leaky gas spring valve for preventing piston overstroke in a free piston stirling engine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996006273A1 (fr) * 1994-08-20 1996-02-29 Karl Obermoser Moteur stirling a pistons synchrones

Also Published As

Publication number Publication date
US5109673A (en) 1992-05-05

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